Learning to love grains, potatoes was key to the evolution of dogs - German Shepherd Dog Forums

Increase font size: 0, 10, 25, 50%

GermanShepherds.com is the premier German Shepherd Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools
Old 01-23-2013, 06:03 PM   #1 (permalink)
jae
Master Member
 
Join Date: Jul 2012
Location: IA
Posts: 701
Default Learning to love grains, potatoes was key to the evolution of dogs

Learning to love cereal was key to the evolution of dogs - The Washington Post
By David Brown, Wednesday, January 23, 1:54 PM


You know that dog biscuit shaped like a bone but made mostly of wheat? The fact that your dog is satisfied with it instead of going for a piece of your thigh may be one of the big reasons why its ancestors evolved from wolves to house pets.
A team of Swedish researchers has compared the genomes of wolves and dogs and found that a big difference between the two is a dog’s ability to easily digest starch. On its way from pack-hunting carnivore to fireside companion, dogs learned to love — or at least live on — wheat, rice, barley, corn and potatoes.

As it turns out, that’s also a change that human beings underwent as they came out of the forest, built permanent settlements and began to grow grain.
“I think it is a striking case of co-evolution,” said Erik Axelsson, a geneticist at Uppsala University. “The fact that we shared a similar environment in the last 10,000 years caused a similar adaptation. And the big change in the environment was the development of agriculture.”
The findings, published Wednesday in the journal Nature, support the hypothesis that dogs evolved from wolves who found a new food source in refuse on the outskirts of human settlements. Eventually they came to tolerate human contact and were brought into the household to be guards, workers and companions.
Another theory is that dogs were descended from wolves captured by hunter-gatherers, who tamed and bred them.
Dog evolution is a contentious subject, and the new findings are unlikely to settle the debate. Among the uncertainties is when some wolves began to evolve into dogs.
Human-tolerant — if not fully domesticated — canids may have existed as long as 33,000 years ago. Archaeological remains reveal dogs and human beings sharing the same graves 11,000 ago. That was at the dawn of agriculture; the two species appear to have been at least acquaintances by then.
“Pretty much everyone without an agenda agrees that we don’t really have a good handle about why wolves domesticated into dogs when they did,” said Adam Boyko, a geneticist at Cornell University who studies dog evolution and was not involved in the new research. “But it does seem reasonable, and in agreement with the fossil and genetic record, that it could have predated agriculture somewhat.”
The evidence of natural selection in the number and efficiency of key digestive enzymes supports the hypothesis that dogs may have domesticated themselves as a way to exploit the garbage of permanent human settlements.
“Humans had nothing to do with it,” said Raymond Coppinger, an emeritus professor of biology and expert on dog evolution at Hampshire College, in Massachusetts. “There was a new niche that was all of a sudden available for somebody to move into. Dogs are selected to scavenge off people.”
Accompanying the dietary change — and probably evolving along with it — were behavior changes that allowed dogs to tolerate living near people and ultimately being adopted by them. The Swedish researchers found strong evidence of genetic differences in brain function — and particularly brain development — between wolves and dogs, which they have not yet analyzed in detail.
In the new study, Axelsson and his colleagues examined DNA from 12 wolves and 60 dogs. The wolf samples were from animals from the United States, Sweden, Russia, Canada and several other northern countries. The dogs were from 14 different breeds.
The researchers compared the DNA sequences of the wolves and dogs (which are subspecies of the same species, Canis lupus) and identified 36 regions in which there differences suggestive of recent natural selection in dogs.
In particular, dogs show changes in genes governing three key steps in the digestion of starch. The first is the breakdown of large carbohydrate molecules into smaller pieces; the second is the chopping of those pieces into sugar molecules; the third is the absorption of those molecules in the intestine.
“It is such a strong signal that it makes us convinced that being able to digest starch efficiently was crucial to dogs. It must have been something that determined whether you were a successful dog or not,” Axelsson said.
The change is at least partly the consequence of dogs having multiple copies of a gene for amylase, an enzyme made by the pancreas that is involved in the first step of starch digestion. Wolves have two copies; dogs have from 4 to 30.
As it happens, amylase “gene duplication” is also a feature of human evolution. Human beings carry more copies of the amylase gene than their primate ancestors. People also produce the enzyme in saliva, which allows the first steps of digestion to occur while the food is still in the mouth. That, in turn, rewards chewing and increase’s the palatability of food.
In dogs, however, the increased amylase activity occurs only in the pancreas. The enzyme isn’t at work in their mouths, probably because the food doesn’t stay there long enough. Dogs may be able to eat human food, but they still wolf it down.
jae is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 01-23-2013, 06:13 PM   #2 (permalink)
Knighted Member
 
Gretchen's Avatar
 
Join Date: Jan 2011
Location: California's Central Coast
Posts: 2,836
Default

I wouldn't say they "love" grains, but since dogs did live with or near humans they would naturally eat what the humans ate or their scraps. Our dog does not like carbs, turns her nose up to a piece of bread or potato. When we go to the pet store and the cashier asks if she can have a cookie, I say sure, but often she spits it out. She does have a sweet tooth, though. Checks every morning to see if the See's Candy mints are still in the bowl on the living room side table.
Gretchen is offline   Reply With Quote Quick reply to this message
Old 01-23-2013, 06:16 PM   #3 (permalink)
Knighted Member
 
Wild Wolf's Avatar
 
Join Date: Dec 2010
Location: Canada
Posts: 3,139
Default

I strongly believe dogs are facultative carnivores.

A carnivore (pron.: /ˈkɑrnɪvɔər/) meaning 'meat eater' (Latin, carne meaning 'flesh' and vorare meaning 'to devour') is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging.[1][2] Animals that depend solely on animal flesh for their nutrient requirements are considered obligate carnivores while those that also consume non-animal food are considered facultative carnivores.[2] Omnivores also consume both animal and non-animal food, and apart from the more general definition, there is no clearly defined ratio of plant to animal material that would distinguish a facultative carnivore from an omnivore, or an omnivore from a facultative herbivore, for that matter.[3] A carnivore that sits at the top of the foodchain is an apex predator.
__________________
SG S-Hunter vom Geistwasser CA CGN TT (Airport Wildlife Control K9)
Zenna vom Geistwasser

"May my enemies live long so they can see me progress."


www.germanshepherdguide.com
Wild Wolf is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the German Shepherd Dog Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 05:39 PM.



Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
SEO by vBSEO 3.3.2
PetGuide.com
Basset Hound Forum Doberman Forum Golden Retriever Forum Beagle Forum
Boxer Forum Dog Forum Pit Bull Forum Poodle Forum
Bulldog Forum Fish Forum Havanese Forum Maltese Forum
Cat Forum German Shepherd Forum Labradoodle Forum Yorkie Forum Hedgehog Forum
Chihuahua Forum Retriever Breeds Cichlid Forum Dart Frog Forum Mice Breeder Forum